Nature and extent of the burden and risks associated with participation, benefit and group relatedness: Patients in the RFD + Local Anesthesia-group and Local Anesthesia-group will undergo a physical examination before and 6 weeks after the intervention, by an independent third party, this will be repeated at 3 and 6 months if abnormalities are observed. At each of these time points the patients will receive questionnaires to fill out. A puncture of a blood vessel is possible, diagnosed by injection of contrast, for which repositioning of the needle is needed. Should accidental intravascular injection of local anesthetic occur, the dose used is low and reports show that intravascular injection of bupivacaine 2,5 mg does not pose clinical problems. The dura can be punctured; as a consequence contrast will flow in the cerebrospinal fluid. The procedure will be stopped and repeated after a few days. In theory a lesion of the nerve root is possible, but the needles are designed to avoid this, this complication has not been seen since more than 10 years. Up till now, a transient pain is occasionally described after the RF treatment. No hypesthesia or motor complications were reported. Since the risks of RF treatment are reported low and more related to needle placement there is no difference in risk and burden between the two treatment groups.